Heating and cooling system



Dec. 6, 1966 L. H. LEONARD, JR 3,289,745

HEATING AND COOLING SYSTEM Filed June 25, 1964 5 Sheets-Sheet l IN VENTOR.

ATTORNEY.

LOUIS H. LEONARD, JR.

1966 I... H. LEONARD, JR 3,289,745

HEATING AND COOLING SYSTEM Filed June 23, 1964 5 Sheets-Sheet 2 9 an Eantiw ILZA L LL] 2 H u i O E (D E INVENTOR. LOUIS H. LEONARD, JR.

W fi/MFZMK M ATTORNEY.

Dec. 6, 1966 H. LEONARD, JR

HEATING AND COOLING SYSTEM 5 Sheets-Sheet 3 Filed June 23, 1964INVENTOR. LOUIS H. LEONARD, JR.

BY I

ATTORNEY.

United States Patent Ofiiice 3,289,745 Patented Dec. 6, 1966 3,289,745HEATING AND COOLING SYSTEM Louis H. Leonard, .Ir., Dewitt, N.Y.,assignor to Carrier Corporation, Syracuse, N.Y., a corporation ofDelaware Filed June 23, 1964, Ser. No. 377,314 12 Claims. (Cl. 165-44)This invention relates to a heating and cooling system and, moreparticularly, to a heat exchanger for heating a load and to heating andcooling capacity control in such a system.

Various types of refrigeration systems, such as absorption systems andrefrigerant compressor systems, are well known in the art. Theconstruction, components and relative association of the components, aswell as the operating characteristics of such systems are also wellknown. However, each system has certain disadvantages as well asparticular advantages, but attempts to provide systems combining theadvantages of accepted systems While avoiding their disadvantages havegenerally resulted in systems which were impractical.

For example. various expedients are known in the art for automaticallycontrolling the capacity of the various systems. In systems utilizing arefrigerant compressor, such control is usually accomplished by varyingthe compressor speed or adjusting guide vanes in the compressor inlet toregulate the flow of refrigerant. My copending United States patentapplication for a Heating and Cooling System, Serial No. 377,319, filedon the same date as the present application, more fully discusses suchprior systems and discloses a system wherein one condensing bundle in asteam condenser is blanketed with a noncondensible refrigerant vapor tocontrol the cooling capacity of the system while another condensing tubebundle in the steam condenser remains effectively free of suchblanketing for providing optimum heating for a load to be heated. Duringwinter heating operation, when cooling is not required, a purge systemis kept in operation to maintain the heating bundle free of anyrefrigerant which may migrate into the steam condenser.

Refrigerant systems which utilize a high speed centrifugal compressorand a relatively high molecular weight refrigerant are known to possessmany theoretical advantages in size, cost and efliciency as is morefully discussed in my prior copending United States patent application,Serial No. 112,679, filed May 25, 1961, for a Method and Apparatus forHeating and Cooling. However, practical problems affect the life andreliability of many such systems, and these problems have greatlyincreased the cost and complexity of the system, so that early systemsof this type have received little general acceptance.

In three-pipe air conditioning installations, both cooling water andheating water are piped throughout the installation so that aircirculating within the various areas can be regulated independently to adesired temperature. As is generally understood, when the cooling demandthroughout the installation is high, the cooling capacity of the systemshould greatly exceed the heating capacity, and under reverseconditions, the heating capacity should greatly exceed the coolingcapacity of the system. To vary the heating and cooling capacities of asystem inversely of each other, as is desirable in a typical three-pipesystem, has required complicated and expensive controls, and manymachines used for simultaneous heating and cooling are too delicate andeasily become inoperative should leakage occur. Furthermore, priormachines have generally been unable to efliciently provide high heatingcapacity at low or zero cooling capacity while maintaining the system innormal heating operation.

A primary object of this invention is to provide a new and improvedheating and cooling system.

A further object is provision of a new and improved heating machine. Arelated object is provision of such a machine, which is operated bysteam for satisfying a demand in addition to heating; for preventing theheating requirement from utilizing the steam required to satisfy theother demand.

A further object is provision of a new and improved heat exchanger. Arelated object is provision of such a heat exchanger in a machine forproviding heating and cooling.

A still further object is provision of a new and improved heating andcooling machine for varying the heating capacity inversely in thecooling capacity of the machine. A related object is provision of such amachine which is particularly suited for use in a three-pipe heating andcooling system.

A still further object is provision in a. heating and cooling machine ofnew and improved means for controlling the heating capacity inversely ofthe cooling capacity.

These and other objects of the invention will be apparent from thefollowing description and the accompanying drawings in which:

FIGURE 1 is a flow diagram of an embodiment of a heating and coolingmachine;

FIGURE 2 is an axial vertical sectional view of a heat exchanger of themachine shown in FIGURE 1, with parts broken away for clearerillustration;

FIGURE 3 is a vertical sectional view of another embodiment of a heatexchanger incorporated within a steam generator of the machine, andtaken generally on the line III-III in FIGURE 4; and

FIGURE 4 is a vertical sectional view taken generally along the line IVIV in FIGURE 3.

The invention is illustrated in the form of apparatus for providingcooling, heating and simultaneous heating and cooling. The system ispreferably airtight and may be considered as having a power sideincluding a circuit for the circulation of a power fluid, and arefrigerant side including a circuit for the flow of a refrigerant fluidunder the influence of drive or operating means on the power side drivenby the power fluid, with the operation of the apparatus regulated by acontrol system.

The invention will be described with reference to a preferred powerfluid, which is water, and a preferred ref rigerant which isoctafluorocyclobutane, commonly referred to as C318 and having achemical formula C F These fluids are particularly preferred because oftheir relative immiscibility and because they are inherently highlystable and do not tend to decompose or chemically react with each otheror other materials in the system, or cause or promote corrosion andundesirable by-products. Also, this refrigerant is a relativelynoncondensible vapor at the temperatures and pressure at which the powerfluid (water) condenses as well as at the usual ambient atmosphericconditions of temperature and pressure. However, other'power fluids andrefrigerants having the desired chemical and physical properties may beutilized within the scope of this invention.

As illustrated in FIGURE 1, the power side includes a suitable steamgenerator 12 and operating means inthe form of a turbocompressor 13including a turbine 14 which receives steam from the steam generator 12and discharges exhaust steam to a steam condenser 16 here shown as partof a composite condensing unit as described in the copending patentapplication of Joseph Embury for a Heat Exchanger Unit, Serial No.377,261 and filed on the same date as the present application. A steamcondensate pump 17 returns the steam condensate from the steam condenser16* through a heat exchanger 18 for providing heating to a load, fromwhich the condensate passes to the steam generator 12 for recirculationthrough the power side of the system. The

turbocompressor 13 preferably has water iubricated bearings and thesteam condensate pump 17 forwards steam condensate through a lubricantline 18' including a lubricant cooling heat exchanger 19* forlubricating these bearings. Leakage of steam and refrigerant between theturbine and the compressor, and the lubricating water, pass through adrain line 18 to the steam condenser 16. In the illustrated apparatusthe steam generator 12 supplies steam at a substantially constantpressure p.s.i.g., for example) as controlled for example, by a constantpressure regulating valve 19 in a steam supply line 19" to the turbine.

The refrigerant side of the system includes a refrigerant compressor 20of the turbocompressor 13. The compressor 20 is drivingly connected withthe turbine 14 for passing compressed refrigerant vapor to a refrigerantcondenser 21 here shown as part of the composite condensing unit,although a separate structure may be employed if desired to condense therefrigerant. Condensed refrigerant passes from the refrigerant condenser21 to a refrigerant subcooler 22 and through a suitable refrigerant flowrestricting means 23 into an evaporator or cooler 24, from which therefrigerant vapor is withdrawn by the refrigerant compressor, thuscompleting the refrigerant circuit of the System. A chilled water line25 extends into the cooler and carries a heat exchange medium, here inthe form of chilled water, which is cooled by the refrigerant andcirculated by means of a chilled water pump 26 to an area having acooling requirement. The cooling capacity of the system varies inproportion to the compressor output.

A cooling tower or condensing water pump 27 circulates tower Waterthrough an inlet line 28 to the refrigerant subcooler 22 and through acondensing tube bundle 22 in the refrigerant condenser 21 and then thesteam condenser 16 and back to the tower through an outlet line 29. Abranch line 30 in the condensing water inlet line 28 provides towerwater to the lubricant water heat exchanger 19 for cooling the lubricantwater, and this branch terminates in the return line 29 to the tower. Ingeneral, control of condensing water temperature and flow rate isunnecesary, thus effectively minimizing scaling of condensing surfacesin the condenser due to average lower temperatures.

The control system regulates the cooling capacity of the machine byvarying the steam condenser pressure as determined by the condensingrate of steam discharged into the steam condenser. The condensing rateof the steam condenser is regulated by controlled blanketing of a tubebundle 34 (which receives the tower water from the refrigerantcondenser) with a noncondensible vapor, herein refrigerant vapor,introduced through a refrigerant line 34' from the cooler 24.

The quantity of noncondensible vapor effectively blanketing the tubebundle 34 of the steam condenser is regulated 'by a modulatingrefrigerant valve 35 in the line 34. The valve 35 is actuated responsiveto chilled water temperature by means of a temperature sensor 37 on thechilled water line 25 so that as the cooling load drops more refrigerantis introduced into the steam condenser 16 thus reducing the steamcondensing rate to increase the steam condenser pressure, and thereforethe temperature of the saturated steam and the turbine dischargepressure to reduce the turbocompressor output and in general speed. Therefrigerant is preferably withdrawn from the steam condenser at aconstant rate, and herein a constant speed water supply pump 38circulates impeller water for operating a jet pump 39 which withdrawsthe noncondensi b le vapor from the steam condenser 16 through a purgeline 40 opening into the throat of the jet pump. Impeller watertemperature i maintained below the saturation temperature of water inthe steam condenser to prevent water from flashing in the jet pump 39,and to this end, the hot vapors withdrawn from the steam condenser arecooled in the cooler 24. The water supply pump 38 further providesmake-up water for the steam generator 12 through a make-up water line40' to the steam condenser 16.

More particularly, after passing the turbine rotor, the steam issaturated and passes through a turbine steam discharge passage 81 andinto the steam condenser 16. The turbocompressor 13 is suitably mountedon an end plate 82 of the steam condenser, as by bolts, with the turbinedischarge passage 81 in communication with a steam inlet port 84 in theend plate. A condensate chamber 86 of the steam condenser 16 is incommunication with the interior of a cylindrical shell 87 of the steamcondenser 16 through a port 88 in the end wall plate 82. Theturbocompressor drain 1%" opens into the condensate chamber 86. Thesteam condensate pump 17 withdraws the steam condensate from thecondensate chamber through a condensate line 1133 and pumps thecondensate back to the heat exchanger 18.

The refrigerant injected into the steam condenser to blanket the tubebundle 34- passes through a refrigerant port 106 in the end of therefrigerant line 34' at the steam condenser steam inlet port 84. Therefrigerant vapor entering the steam condenser 16 envelops the tubebundle 34 thereby insulating the tubes to reduce the steam condensingcapacity and raise the pressure. The rate of condensing steam in thesteam condenser is proportional to the cooling capacity of the system sothat the flow rate of the condensate to the heat exchanger 18 issimilarly proportional.

The purge line 40 opens into a side of the steam con densate chamber 86at a level to withdraw steam condensate from the chamber shouldcondensate level rise too high. Responsive to a low condensate level inthe condensate chamber 86, a float actuated sensor 112 opens a normallyclosed shut-off valve 113 in the make-up water line 40' from the watersupply pump 38, to maintain a mini-mum level of condensate in thechamber 86.

The cooler refrigerant inlet opens into a refrigerant pan 127 spacedabove the bottom of the cooler shell 126. A U-tube bundle 128 of thechilled water line 25 is within the refrigerant pan 127 so that duringnormal cooling operation, the tubes are flooded by boiling refrigerant.As the refrigerant evaporates, the vapor passes into a refrigerantchamber 129 in an upper portion of the cooler shell 126 above the pan. Arefrigerant outlet 130 opens into an upper portion of the refrigerantchamber 129 and is connected with the compressor inlet by the suctionline 121. The portion of the cooler 24 below the refrigerant pan 127provides a water sump 132 which contains the jet pump 39 so that theimpeller water and refrigerant and any water vapors purged from thesteam condenser 16 are injected into the sump 132 and sump water iswithdrawn from the sump through a pump supply line 133 so that the sumpwater is recirculated through the sump. During normal cooling operation,refrigerant in the sump is a vapor which passes upwardly about the leftend of the refrigerant pan 127 and into the refrigerant chamber 129 fromwhich it is withdrawn through the suction line 121. Water in therefrigerant chamber 129 collects on top of the liquid refrigerant in thepan 127. The chilled water tube bundle 128 is spaced inwardly from theleft end wall of the pan to form a relatively quiet area of liquidrefrigerant upon which any water in the pan collects in a relativelyquiet pool and flows through a suitable weir or port 134 in the end ofthe pan and into the sump 132. Thus, means is provided for separatingrefrigerant fluid and power fluid, and for returning these fluids forreuse in the system.

A hot gas bypass including a hot gas bypass line 136 having a modulatingrefrigerant valve 137 with a sensor 138 responsive to total pressure inthe steam condenser 16 is provided to increase the useful heatingcapacity range at low or Zero cooling capacity, as is more fullydiscussed in my previously mentioned Heating and Cooling Systemapplication.

To summarize the cooling operation of the machine, if the chilled watertemperature drops, indicating a reduced cooling requirement, themodulating refrigerant valve 35 in the refrigerant line 34' to the steamcondenser 16 is opened additionally to permit more refrigerant to enterthe steam condenser for blanketing the first condensing bundle 34 toreduce the steam condensing capacity and to increase steam condenserpressure and the turbine discharge pressure, thus slowing theturbocompressor and causing the compressor 20 to deliver a smallerquantity of refrigerant to the coller 24, thereby reducing the coolingcapacity of the system and increasing the temperature of the leavingchilled water. Should the chilled water temperature rise, indicating arise in the cooling requirement, the refrigerant valve 35 is closedsufficiently and less refrigerant is injected into the steam condenserso that the quantity of refrigerant vapor effectively blanketing thecondensing bundle 34 is reduced as the constant rate purge withdrawsrefrigerant from the steam condenser, thus increasing the coolingcapacity.

With reference to FIGURE 2, the heat exchanger 18 is surmounted on thesteam generator 12 by means of a pair of vertical supporting pipes 140opening into the steam generator and a cylindrical steam jacket 141. Thejacket 141 is secured in fluid tight manner about a left end of acylindrical shell 142. The shell encases a straight through tube bundle143 opening at one end into a suitable header 144 having an inlet 145and an outlet 146 for circulating a heating medium, preferably water,through a heating line 146' and the tube bundle, and at an opposite endopening into a return header 147 at the opposite end of the shell 142.Aternatively, a U-tube bundle and only an inlet-outlet header may beprovided. A heating water pump 148 in the line 146 circulates theheating water to a load having a heating requirement.

The steam condensate return line 103 from the steam condensate pump 17opens through the jacket 141 for discharging steam condensate from thesteam condenser 16 through an open top portion 149 of the shell 142which forms a container for the condensate.

During normal partial load operation of the heating and cooling machine,the tube bundle 143 is at least partially covered by the condensate forreducing heat transfer from the steam to the bundle, thereby reducingthe heating capacity of the system and insuring sufficient steam for thecooling cycle requirements. Both the condensate from the steam enteringdirectly from the steam generator 12 through the supporting pipes 140for heating the wa ter within the tube bundle 143, and the condensatefrom the steam condenser 16 entering through the steam condensate returnline 103, are returned to the steam generator 12 through a condensatereturn conduit 150 communicating with a lower portion of the shell 142and opening into one of the supporting pipes 140. A restricting orifice151 is provided in the condensate return conduit 150 for restricting theflow of condensate back to the steam generator 12 via that route. Theorifice 151 is of such size and at such a position below the bottom ofthe open top portion 149 of the shell 142 so that at full coolingcapacity, the steam condensate barely overflows through the open top 149and the head of condensate above the orifice causes full condensateflow, corresponding to full boiler capacity (for example 1000 pounds ofsteam or condensate per hour), through the orifice 151 by gravity. Asthe cooling capacity drops, the flow rate of steam condensate into theshell 142 drops proportionally, so that the head of condensate in theshell 142 also drops to an equilibrium level at which the flow ratethrough the orifice 151 equals the flow rate of condensate through thereturn line 103 and the rate at which the steam heating the tube bundle143 condenses in the shell 142. About ten percent of the tubes of theheating bundle 143 are preferably above the top possible level of thecovering condensate in the shell 142, that is, above the elevation ofthe bottom of the open top portion 149 of the shell 142, so that someheat is always provided to the load.

Thus, for any given flow rate of condensate from the steam condenserthrough the steam condensate return line 103, a given level ofcondensate is maintained within the shell 142 for partially covering thetube bundle 143 and thereby regulating the maximum amount of heattransferred between the steam and the heating water to the load. Forexample, with full cooling, the pressure drop across the orifice will beenough to submerge the tube bundle almost to the top, so that only thetop tubes are available for heating.

A manually operable shut-0ff valve 152 may also be provided in thereturn conduit to render the orifice 151 inoperative for regulating thepassage of condensate from the shell 142 to the steam generator 12, anda manually operable regulating valve 153 may be provided in a secondreturn conduit 154 from the shell 142 to the pipe 140 for manuallyregulating the condensate level in the shell 142.

It should be noted that a closed steam circuit is provided in theheating and cooling machine so that make-up water need not be added tothe system and boiler Water treatment is not required. A steam generatorwater level control may be provided for regulating the flow of steamcondensate through the steam condensate return line 103, and thusprevent an excessive accumulation of water in the steam generator underunusual circumstances, but under normal operating condition such acontrol does not affect the rate at which condensate is formed in thesteam condenser 16 and passed to the heat exchanger 18.

Another embodiment of a heat exchanger is shown in FIGURES 3 and 4, andis substantially the same as the previously described heat exchanger 18except as follows: The heat exchanger 160 is within a shell 161 of thesteam generator 12 which may be of any suitable fire tube type. The heatexchanger 160 includes a tube bundle 162 in lieu of the tube bundle 143,and a trough 163 in lieu of the shell'142. The tube bundle may bestraight through tubes opening into opposed headers of the steamgenerator, or, as shown, U-tubes opening into a header, as 165, insuitable communication with an inlet 166 and an outlet 167 for theheating line 146'. The trough 163 is in Sealed engagement with theheader and an opposed plate, for containing steam condensate enteringthrough the steam condensate return line 103, and condensed in thetrough 163, as previously described. Herein the line 103 extends throughthe steam condenser shell 161 and opens above the trough 163. Arestricting orifice 168 is provided in a first condensate return conduit169 at the bottom of the trough 163, in lieu of the orifice 151 in theprior embodiment, and a manually operable shutoff valve 170 may beprovided in the return conduit 169 to render the orifice inoperative sothat heating capacity may be regulated by a manually operable regulatingvalve 171 in a second return conduit 172 providing communication betweenthe bottom of the trough 163 and the body of water within the steamgenerator 12, all as previously described. The valves 1'70 and 171 areoutside of the shell of the steam generator.

About ten percent of the tube bundle 162 is above top edges 172 of thetrough 163 to provide some heating at full cooling capacity.

The heat exchangers herein described effectively eliminate Water hammerand, during winter heating when cooling is not required, a shutoff valve173 (FIGURE 1) in the steam line 19 to the turbine 14 may be closed. Thesteam condensate pump 17 and the water supply pump 38 remain inoperation for purging refrigerant from, and providing adequate water forthe steam generator 12.

While a preferred embodiment of the invention has been described andillustrated, it will be understood that the invention is not limitedthereto since it may be otherwise embodied within the scope of thefollowing claims.

I claim:

1. A heating and cooling machine comprising, a refrigerant side operablefor cooling a load, a steam generator, a steam condenser, operatingmeans for receiving steam from said steam generator and responsivethereto operating said refrigerant side and discharging the steam intosaid steam condenser, means for regulating the steam condensing rate ofsaid steam condenser in proportion to the cooling capacity of saidrefrigerant side, means including a heat exchanger for receiving steamfrom said steam generator and having a tube bundle for circulating aheating medium to be heated by the steam for heating a load, containermeans for holding water about said bundle to reduce heat transfer fromthe steam to said bundle and therefore the heating capacity of the heatexchanger, means for passing said steam condensate from said steamcondenser to said container means, and regulating means for coveringsaid bundle with steam condensate in proportion to said steam condensingrate of said steam condenser, whereby the heating and cooling capacitiesof the system vary inversely of each other.

2. The machine of claim 1 wherein said heat exchanger is surmounted onsaid steam generator.

3. The machine of claim 1 wherein said container means comprises a shellenveloping said tube bundle.

4. The machine of claim 3 wherein a jacket envelops a portion of saidshell, conduit means providing communication between said steamgenerator and said jacket for the passage of steam into said jacket, anupper portion of said shell within said jacket having an opening for thepassage of the steam from within said jacket into said shell to heatsaid tube bundle, a portion of said tube bundle being at an elevationabove said opening to be heated by the steam for supplying heat to theload when the shell is filled with condensate overflowing through saidopening and into said jacket.

5. The machine of claim 4 wherein said conduit means further serves toreturn steam condensate from said jacket to said steam generator.

6. The machine of claim 5 wherein said conduit means mountssaid shelland jacket on said steam generator.

7. The machine of claim 1 wherein said heat exchanger is within saidsteam generator.

8. The machine of claim 1 wherein said containing means comprise atrough, and said tube bundle is within said trough.

' 9. The machine of claim 8 wherein said trough has an open top for theentry of steam in the steam generator into heat exchange relationshipwith said tube bundle to heat the heating medium, a portion of said tubebundle being at an elevation above the top of said trough to be heatedby the steam for supplying heat to the load when said shell is filledwith condensate overflowing the top of the trough.

10. The machine of claim 1, and said regulating means comprising aconduit for the passage of condensate out of said container means, andmeans in said conduit for restricting the flow of said condensate.

11. The machine of claim 10 wherein the last said means comprises afixed orifice.

12. The machine of claim 10 herein the last said means comprises acondensate flow regulating valve.

References Cited by the Examiner UNITED STATES PATENTS 2,793,502 5/1957Riehl 6-2 2,830,797 4/1958 Garland 165-146 3,153,442 10/1964 Silvern165-50 ROBERT A; OLEARY, Primary Examiner.

C. SUKALO, Assistant Examiner.

1. A HEATING AND COOLING MACHINE COMPRISING, A REFRIGERANT SIDE OPERABLEFOR COOLING A LOAD, A STEA, GENERATOR, A STEAM CONDENSER, OPERATINGMEANS FOR RECEIVING STEAM FROM SAID STEAM GENERATOR AND RESPONSIVETHERETO OPERATING SAID REFRIGERANT SIDE AND DISCHARGING THE STEAM INTOSAID STEAM CONDENSER, MEANS FOR REGULATING THE STEAM CONDENSING RATE OFSAID STEAM CONDENSER IS PROPORTION TO THE COOLING CAPACITY OF SAIDREFRIGERANT SIDE, MEANS INCLUDING A HEAT EXCHANGE FOR RECEIVING STEAMFROM SAID STEAM GENERATOR AND HAVING A TUBE BUNDLE FOR CIRCULATING AHEATING MEDIUM TO BE HEATED BY THE STEAM FOR HEATING A LOAD, CONTAINERMEANS FORHOLDING WATER ABOUT SAID BUNDLE TO REDUCE HEAT TRANSFER FROMTHE STEAM TO SAID BUNDLE AND THEREOF THE HEATING CAPACITY OF THE HEATEXCHANGE, MEANS FOR PASSING SAID STEAM CONDENSATE FROM SAID STEAMCONDENSER TO SAID CONTAINER MEANS, AND REGULATING MEANS FOR COVERINGSAID BUNDLE WITH STEAM CONDENSATE IN PROPORTION TO SAID STEAM CONDENSINGRATE OF SAID STEAM CONDENSER, WHEREBY THE HEATING AND COOLING CAPACITIESOF THE SYSTEM VARY INVERSELY OF EACH OTHER.